Tin Disulfide Nanosheets with Active-Site-Enriched Surface Interfacially Bonded on Reduced Graphene Oxide Sheets as Ultra-Robust Anode for Lithium and Sodium Storage.

Two-dimensional (2D) tin disulfide (SnS2) has attracted intensive research owing to its high specific capacity for Li and Na storage, natural abundance, as well as environmental friendliness. However, the poor reaction kinetics, low intrinsic electrical conductivity, and severe volumetric variation upon cycling processes of SnS2 impede its widespread application. In this work, SnS2 nanosheets with active-site-enriched surface intimately grown on reduced graphene oxide (rGO) via C-O-Sn chemical bonds are prepared. The aligning affords more active sites for electrode reaction and short transport pathways for Li+/Na+ and electrons. The strong chemical bonding enhances the interfacial affinity of SnS2 with rGO and inhibits the detachment of active SnS2 from rGO during repeated charge and discharge processes, which can ensure an integrated electrode structure. The 3D conductive and flexible rGO network improves the conductivity of the entire composite and buffers the volume change of SnS2 upon charge/discharge. These advantages enable the designed SnS2/rGO nanocomposite to have high specific capacity, superior rate capability, and outstanding long-cycling stability for both Li and Na storage.

(101) Plane-Oriented SnS2 Nanoplates with Carbon Coating: A High-Rate and Cycle-Stable Anode Material for Lithium Ion Batteries.

Tin disulfide is considered to be a promising anode material for Li ion batteries because of its high theoretical capacity as well as its natural abundance of sulfur and tin. Practical implementation of tin disulfide is, however, strongly hindered by inferior rate performance and poor cycling stability of unoptimized material. In this work, carbon-encapsulated tin disulfide nanoplates with a (101) plane orientation are prepared via a facile hydrothermal method, using polyethylene glycol as a surfactant to guide the crystal growth orientation, followed by a low-temperature carbon-coating process. Fast lithium ion diffusion channels are abundant and well-exposed on the surface of such obtained tin disulfide nanoplates, while the designed microstructure allows the effective decrease of the Li ion diffusion length in the electrode material. In addition, the outer carbon layer enhances the microscopic electrical conductivity and buffers the volumetric changes of the active particles during cycling. The optimized, carbon coated tin disulfide (101) nanoplates deliver a very high reversible capacity (960 mAh g-1 at a current density of 0.1 A g-1), superior rate capability (796 mAh g-1 at a current density as high as 2 A g-1), and an excellent cycling stability of 0.5 A g-1 for 300 cycles, with only 0.05% capacity decay per cycle.